* In case an emergency mass vaccination for an unforeseen public health threat is organised by the public health authorities, outside the routine immunization program, vaccines can be administered at any time during the study period provided it is licensed and used according to its Summary of Product Characteristics or Prescribing Information and according to the local governmental recommendations and that a written approval of the Sponsor is provided. Vaccines that are recommended for subjects with an increased risk of bacterial infection, can be administered at any time to the subjects enrolled in the At-risk group.